The original micromagnetism is quasi-classical since it is based on the assumption that the magnetization magnitude is unchanged in the whole magnetic system, so the theory is only strictly valid at zero temperature. To generalize its applicability to elevated temperatures, Garanin proposed the Landau–Lifshitz–Bloch equation by further considering the random fields arising from the heat effects and allowing the length variations of magnetic moments. However, the expressions for the fields and changes are usually complicated, or even impossibl...
